As cellular networks become more congested, network operators continue to deploy smaller cells on several orders of magnitude to meet projected demands. The presence of these smaller cells helps offload traffic from the macro cells, but may cause unwanted interference. In some situations, smaller cells may not be actively serving a user, but may continue to transmit at least the downlink common channels. This continued transmission may cause undesirable interference, especially where the density of access nodes is high. Additionally, these continued transmissions may expend energy unnecessarily. Therefore it may be beneficial to have access nodes enter a dormant state when they are not serving a user to limit interference and conserve power.
While placing the access nodes in a dormant state may prevent interference and save power, it creates new challenges for discovery and reactivation of the dormant access nodes. Generally, discovery techniques have relied upon a macro cell (provided by an evolved node B (“eNB”)) knowing the location of user equipment and small cells so that the eNB may wake up the small cell when a UE is nearby. This approach has certain drawbacks. First, the position of a UE or small cell may not be accurate or available in some situations, particularly in indoor environments, preventing the eNB from correctly determining if the UE is near a dormant small cell. Second, the eNB may not be aware of some small cells, such as those not deployed by the operator of the eNB, such that the eNB would not be able to wake up these small cells if a UE was nearby.